Remove resolveCanonicalUsage method

[robertbrignull]

Another benefit of the modeleing store is that we no longer need the resolveCanonicalUsage method.

This was needed because we were passing Method objects to and from the webview and this caused them to become new javascript objects. We now keep the canonical objects purely on the extension host side, so when jumping to a usage we already have the canonical objects available.

When testing this, remember to merge in #2977. These do not conflict, but jumping to usages does not work without that PR.

Checklist

• CHANGELOG.md has been updated to incorporate all user visible changes made by this pull request.
• Issues have been created for any UI or other user-facing changes made by this pull request.
• [Maintainers only] If this pull request makes user-facing changes that require documentation changes, open a corresponding docs pull request in the github/codeql repo and add the ready-for-doc-review label there.

[koesie10]

In #2976 I do need this method (although I've renamed it as resolveUsageTreeViewItem) since I'm creating separate tree view items here. Would it make sense to first review #2976 and close this PR if that PR gets merged?

[robertbrignull]

Sounds good. I'll take a look at that other PR.

[robertbrignull]

Closing as the method is now used by #2976